Drosera x obovata Mert. & Koch = Drosera anglica x Drosera rotundifolia, syn.: Drosera longifolia subsp. obovata (Mert. & Koch), Drosera obovata Mert. & KochEN: Obovate-leaved Sundew, Great x Round-leaved Sundew, DE: Bastard-Sonnentau, Breitblattriger SonnentauSlo.: dolgolistna x okroglolistna rosika (krianec)Dat.: Aug. 29. 2008Lat.: 45.82724 Long.: 14,59427Code: Bot_291/2008_DSC2740Habitat: semi ruderal, partly grass overgrown, wet ground near water ditch and local paved road; flat terrain; full sun; elevation 500 m (1.650 feet); average precipitations 1.500-1.700 mm/year, average temperature 8-9 deg C, Dinaric phytogeographical region. Substratum: soil.Place: Mija dolina valley, southeast of settlement Logarji; next to the road toward Kaplanovo, Dolenjska, Slovenia EC Comment: Drosera x obovata is a carnivorous sterile hybrid of parents Drosera anglica and Drosera rotundifolia and probably the rarest taxon of this genus in Slovenia. As all others it is a plant of wetlands and thus endangered, in decline and protected by law. Distinguishing between different species of genus Drosera is not always easy in the field. The plants are variable and individual traits of different species frequently overlap (Ref. 1 and 2). Nevertheless, looking on these pictures it is evident that non-roundish leaves and flowering stalks, which are much longer than the longest leaves reliably eliminates Drosera rotundifolia and Drosera intermedia from a list of possible determinations. Between remaining two options in Slovenia namely Drosera anglica and Drosera x obovata the last one seems considerably better. The Ref.:1 showed that the ratio between leaf blade length to its width is the most practical and reliable trait in distinguishing Drosera x obovata from its parents. Overage ratio specified in literature is 7 (Ref.:1) and 6 (Ref.: 2 and 3) for Drosera anglica and 3.2 (Ref. 1), 2.3 (Ref.: 2) and 2.5 (Ref.: 3) for Drosera x obovata. Measured ratio of the shown plant was 2.9 (SD=0.4, N=4). This clearly speaks in favor of Drosera x obovata. Also fruits seemed to be to some extent atrophied, or at least clearly not 'much longer than calix' as should be with Drosera anglica according to Ref.: 2. Two of five shown fruits on picture 10a have only slightly longer fruits than calyxes, remaining seem shorter and somewhat deformed. This too seems to support Drosera x obovata as proper determination. One of the parent Drosera rotundifolia was found very near this find.Pravilnik o uvrstitvi ogroenih rastlinskih in ivalskih vrst v rdei seznam, Uradni list RS, t. 82/2002 (Regulation of enlisting of endangered plant and animal species onto Red List, Official Gazette of Republic Slovenia, no. 82/2002) (2002). Enlisted in the Slovene Red List of rare and endangered species, marked by "V" representing a vulnerable species.Ref.:(1) Y. Hoyo, S. Tsuyuzaki, Characteristics of leaf shapes among two parental Drosera species and a hybrid examined by canonical discriminant analysis and a hierarchical Bayesian model, American Journal of Botany 100(5) (2013); available at:
onlinelibrary.wiley.com/doi/full/10.3732/ajb.1200510 (accessed Oct. 30 2018)(2) M.A. Fischer, W. Adler, K. Oswald, Exkursionsflora fr sterreich, Liechtenstein und Sdtirol, LO Landesmuseen, Linz, Austria (2005), p 385.(3) A. Martini et all., Mala Flora Slovenije (Flora of Slovenia - Key) (in Slovenian), Tehnina Zaloba Slovenije (2007), p 242. (4) K. Lauber and G. Wagner, Flora Helvetica, 5. Auflage, Haupt (2012), p 696.
